Piston pump having non-collapsible rolling diaphragm



J. F. TAPLIN Nov. 15, 1966 PISTON PUMP HAVING NON-COLLAPSIBLE ROLLING DIAPHRAGM Filed June 30, 1964 United States Patent 3,285,191 PISTON PUMP HAVING NON-COLLAPSIBLE ROLLING DIAPHRAGM John F. Taplin, Sewall St., West Newton, Mass. Filed June 30, 1964, Ser. No. 379,143 2 Claims. (Cl. 103-150) This application is a continuation-in-part of my copending patent application Ser. No. 341,889 filed February 3, 1964, for Piston Pump Having Rolling Diaphragm disclosing means for precluding pressure reversal and collapse of rolling diaphragms.

This invention relates to piston pumps having rolling diaphragms.

The rolling diaphragms of such piston pumps have a radially outer fixed flange portion clamped to the cylinder body of the pump and a radially inner flange portion which is secured to the top of the piston of the pump. The rolling diaphragm further includes an intermediate portion known as the rolling wall. During the suction stroke of the piston pump the rolling wall of the diaphragm rolls off the piston side wall onto the cylinder side wall. Thereafter during the compression stroke of the piston pump the rolling wall performs a reverse movement, i.e. it rolls off the side wall of the cylinder onto the side wall of the piston. The rolling diaphragm of such a piston pump subdivides the cylinder body into two chambers. One of these two chambers is the pump chamber into which a gas or liquid is sucked during the suction stroke of the piston pump, and out of which the gas or liquid is pressed during the following compression stroke of the piston of the pump. The other of the two chambers into which the cylinder body is subdivided by the rolling diaphragm may be referred-to as the inactive chamber since the gas or liquid to be moved by the pump never enters into that chamber.

In order for a piston pump having a rolling diaphragm to properly perform, the pressure in the pump chamber should preferably always exceed the pressure in the inactive chamber. The term pressure reversal refers to a condition wherein the pressure in the inactive chamber exceeds the pressure in the pump chamber. Pressure reversal may result in a collapse of the rolling diaphragm which, in turn, renders the pump inoperative.

It is, therefore, a principal object of this invention to provide reciprocating piston pumps having rolling diaphragms which pumps are not subject to pressure reversal and to collapse of their rolling diaphragm.

In a piston pump having a rolling diaphragm wherein the inactive chamber is freely vented the degree of pressure-build-up in the inactive chamber depends upon the size of the latter, the velocity of the reciprocating movement of the piston, the area of the venting or air dumping orifice, etc. One or more of these parameters may unavoidably, or necessarily, be such as to establish a tendency of pressure reversal and collapse of the rolling diaphragm.

It is, therefore, another object of the invention to provide piston pumps having rolling diaphragms which pumps depart from the heretofore adhered-to principle of freely venting the inactive chamber to atmosphere, and wherein safer and more effective means are used for precluding pressure reversal and collapse of the rolling diaphragm.

The present invention is concerned with means other than those disclosed in my forementioned patent application for achieving the same end.

The foregoing and other general and special objects of the invention and advantages thereof will more clearly appear from the following description of the invention, as illustrated in the accompanying drawing showing in part a vertical section, and in part a side elevation, of a piston pump embodying the present invention.

Referring now to the drawing, numeral 1 has been applied to generally indicate a cylinder body including a central portion 2 and two axially outer portions 3. Central portion 2 is provided with flanges 4, and the axially outer portions 3 are clamped against flanges 4 by the screws 5. The central portion 2 of cylinder body 1 accommodates an integral pair of reciprocating tandem pistons 6. Each piston 6 defines a gap 7 between the radially outer lateral cylindrical surface 8 thereof and the radially inner lateral cylindrical surface 9 of portion 2 of cylinder body 1. The pump comprises further a pair of rolling diaphragms. Each rolling diaphragm includes a radially outer flange portion 10 clamped between parts 3 and 4, a rolling wall 11 arranged inside of gap 7 and a radially inner flange portion 12 secured to an end surface of a piston 6. Rolling diaphragms 10, 11, 12 subdivide the inside of cylinder body 1 into a pair of axially outer pump chambers 13 and an axially inner inactive chamber 14. Each axially outer portion 3 of cylinder body 1 defines a compression outlet 15 controlled by a spring-biased check valve 16 and a suction inlet 17 controlled by a spring-biased check valve 18. The upper'inlet 17 includes a venturi passage 19, i.e. a passageway suction having a-relatively restricted cross-sectional area wherein flow velocity is relatively high. The point of relatively restricted cross-sectional area of the venturi passageway 19 is arranged between an upstream end and a downstream end thereof, both these ends having a relatively large cross-sectional area. A duct or passageway 20 connects the region of minimal cross-sectional'area of venturi passageway 19 to inactive chamber 14.

Pistons 6 may be operated or reciprocated by means of drive lever 21 fulcrummed at 22 on cylinder body 1 and pivotally connected to the piston unit 6, 6 at 23. Duct or passageway 24 connects the downstream end of venturi passageway 19 to the lower check-valve-controlled suction inlet 17. Bellows 25 seals lateral opening 26 in cylinder body 1 provided therein for the passage of drive lever 21.

During the downward stroke of both pistons 6 effected by means of drive lever 21 gas is admitted through the upper suction inlet 17 and venturi passageway 19 into the upper pump chamber 13 and simultaneously gas under pressure is expelled from the lower pump chamber 13 through the lower check-valve-controlled pressure outlet 15. During the downward stroke of both pistons 6 inactive chamber 14 is evacuated through duct or passageway 20 by the action of the rapid flow of gas through venturi passageway 19.

During the upward stroke of both tandem pistons 6 gas is admitted through venturi passageway 19 and the lower suction inlet 17 to the lower pump chamber 13 and gas under pressure is expelled from the upper pump chamber 13 through the upper pressure outlet 15.

Simultaneously inactive chamber 14 is evacuated, or the vacuum prevailing therein maintained, by the action of the rapid flow of gas through venturi passageway 19.

It will be understood that I have illustrated and described a preferred embodiment of my invent-ion and that various alterations may be made in the details thereof without departing from the invention as defined in the appended claims.

I claim as my invention:

1. A piston pump comprising in combination:

(a) a cylinder body having a valve-controlled suction inlet at each end surface thereof and having a valvecontrolled compression outlet at each end surface thereof, said suction inlet at one end surface of said cylinder body including a zone of restricted crosssectional area wherein flow velocity is relatively high and pressure relatively low, said zone of restricted cross-sectional area being arranged between an upstream zone of larger cross-sectional area and a downstream zone of larger cross-sectional area;

(b) duct means connecting said suction inlet at the other end surface of said cylinder body to said downstream zone of larger cross-sectional area of said suction inlet at said one end surface of said cylinder body;

(c) an integral pair of reciprocating tandem pistons inside said cylinder body, each of said pair of pistons defining a gap between the radially outer lateral surface thereof and the radially inner lateral surface of said cylinder body; 1

(d) a pair of rolling .diaphragms each having a radially outer flange portion secured to said cylinder body, a radially inner flange portion secured to one of said pair of pistons and a rolling wall intermediate said radially outer flange portion and said radially inner flange portion arranged-in said gap defined by one of said pair of pistons, said pair of diaphragms subdividing said cylinder body into a pair of axially outer pump chambers and an axially inner inactive chamber; and

(e) duct means connecting said zone of restricted crosssectional area of said suction inlet at one end surface of said cylinder body with said inactive chamber to limit the pressure prevailing inside of said inactive chamber.

'2. A piston pump comprising in combination:

(a) a cylinder body having a suction inlet at each end surface thereof and having a compression outlet at each end surface thereof;

('b) a check valve arranged in each suction inlet to allow admission of fluid into said cylinder body;

(0) a check valve arranged in each compression outlet to allow expulsion of fluid from said cylinder body;

((1) a venturi tube arranged in said suction inlet at one end surface of said cylinder body at a point upstream of said check valve in said suction inlet, said venturi tube having an upstream portion and a downstream portion both of relatively large cross-sectional area and said venturi tube having an intermediate portion of relatively small cross-sectional area;

(e) duct means connecting said downstream portion of said venturi tube to said suction inlet at the other end surface of said cylinder body;

(f) an integral pair of reciprocating tandem pistons inside said cylinder body, each of said pair of pistons defining a gap between the radially outer lateral surface thereof and the radially inner lateral surface of said cylinder body;

(g) a pair of rolling diaphragms each having a radially outer flange portion secured to said cylinder body, a radially inner flange portion secured to one of said pair of pistons and a rolling Wall intermediate said radially outer flange portion and said radially inner flange portion arranged in said gap defined by one of said pair of pistons, said pair ofdiaphragms subdividing said cylinder body into a pair of axially outer pump chambers and an axially inner inactive chamber; and

(h) duct means connecting said intermediate portion of relatively small cross-sectional area of said venturi tube with said inactive chamber to limit the pressure prevailing inside said inactive chamber by the action of said venturi tube.

References Cited by the Examiner UNITED STATES PATENTS 2,150,487 3/1939 Brown 230-206 2,973,717 3/1961 Kendig 103l52 3,027,848 4/1962 Merkle 103-15() FOREIGN PATENTS 8,851 1896 Great Britain.

ROBERT M. WALKER, Primary Examiner. 

1. A PISTON PUMP COMPRISING IN COMBINATION: (A) A CYLINDER BODY HAVING A VALVE-CONTROLLED SUCTION INLET AT EACH END SURFACE THEREOF AND HAVING A VALVECONTROLLED COMPRESSION OUTLET AT EACH END SURFACE THEREOF, SAID SUCTION INLET AT ONE END SURFACE OF SAIC CYLINDER BODY INCLUDING A ZONE OF RESTRICTED CROSSSECTIONAL AREA WHEREIN FLOW VELOCITY IS REALATIVELY HIGH AND PRESSURE RELATIVELY LOW, SAID ZONE OF RESTRICTED CROSS-SECTIONAL AREA BEING ARRANGED BETWEEN AN UPSTREAM ZONE OF LARGER CROSS-SECTIONAL AREA AND A DOWNSTREAM ZONE OF LARGE CROSS-SECTIONAL AREA; (B) DUCT MEANS CONNECTING SAID SUCTION INLET AT THE OTHER END SURFACE OF SAID CYLINDER BODY TO SAID DOWNSTREAM ZONE OF LARGER CROSS-SECTIONAL AREA OF SAID SUCTION INLET AT SAID ONE END SURFACE OF SAID CYLIDER BODY; (C) AN INTEGRAL PAIR OF RECIRPOCATING TANDEM PISTONS INSIDE SAID CYLINDER BODY, EACH OF SAID PAIR OF PISTONS DEFINING A GAP BETWEEN THE RADIALLY OUTER LATERAL SURFACE THEREOF AND THE RADIALLY INNER LATERAL SURFACE OF SAID CYLINDER BODY; (D) A PAIR OF ROLLING DIAPHRAGMS EACH HAVING A RADIALLY OUTER FLANGE PORTION SECURED TO SAID CYLINDER BODY, A RADIALLY INNER FLANGE PORTION SECURED TO ONE OF SAID PAIR OF PISTONS AND A ROLLING WALL INTERMEDIATE SAID RADIALLY OUTER FLANGE PORTION AND SAID RADIALLY INNER FLANGE PORTION ARRANGED IN SAID GAP DEFINED BY ONE OF SAID PAIR OF PISTONS, SAID PAIR OF DIAPHRAGMS SUBDIVIDING SAID CYLINDER BODY INTO A PAIR OF AXIALLY OUTER PUMP CHAMBERS AND AN AXIALLY INNER INACTIVE CHAMBER; AND (E) DUCT MEANS CONNECTING SAID ZONE OF RESTRICTED CROSSSECTIONAL AREA OF SAID SUCTION INLET AT ONE END SURFACE OF SAID CYLINDER BODY WITH SAID INACTIVE CHAMBER TO LIMIT THE PRESSURE PREVAILING INSIDE OF SAID INACTIVE CHAMBER. 